Sander Used in Particular for Sanding of Flat, Concave, and Covex Surfaces and the Method of its Utilsation

ABSTRACT

The sander for sanding particularly of the flat, concave and convex surfaces and the method of its usage is based on the fact, that the sanding tool (paper, linen or other carrier with sanding abrasive layer) is pressed onto the grinded surface by means of a flexible pressure plate able to copy the concave and convex surfaces with the possibility to set accurately the radius of this curve. The principle of the technical solution of the invention of the flexible pressure plate consists in the fact, that the pressure generated during the work onto the body, handle, or handles of the sander with mechanical drive is transferred onto this pressure plate at least at two points simultaneously or over at least one balance beam.

TECHNICAL AREA

The invention concerns manual sander or sander with a drive, designed in particular for sanding of flat, concave, bulging, dome-shaped, hollowed-out, cored, and convex surfaces, and the method of sanding with the use of the above-mentioned tool.

CURRENT STATUS OF TECHNOLOGY

For manual sanding of flat surfaces are currently used either various hand tools such as sanding blocks and sanding planes or mechanically driven, vibrating, band-type or linear sanders of different shapes and sizes. For sanding of concave and convex surfaces are used similar tools but since these tools are designed in particular for sanding of flat surfaces, the resulting ideal sanding of the required convex or concave curves depends to a larger part on the skills of the worker carrying out the operation.

For sanding of large flat surfaces, it is advantageous to work with tools with largest possible working surfaces in order to achieve high output but mainly due to the fact, that when using such tools, it is easier to achieve ideal plane surface. One of the disadvantages of using these tools is the fact, that the larger the working surface, the more difficult and strenuous is the work due to resistance and inertial forces. Another disadvantage is the fact, that when using the tools with a large working area, it is difficult to achieve applying of evenly distributed pressure of the working surface on the surface being grinded. The result is usually a compromise, in terms of which the maximum length of the working area of the hand-held, mechanically driven sanders fluctuates around 50 cm and the total area around 250 cm². In the case of manual sanding planes (blocks) without mechanical drive, the disadvantage of inertial forces does not apply and for this reason, it is possible to extend substantially the working length and to increase the working area of these tools. However, the other disadvantages remain and, in addition, working with such tools is very demanding physically.

The same technology is used for manual sanding of concave or convex surfaces, while for the sanders with mechanical drive are used the tools with partly flexible working area optimised for the dimensions of the concave or convex curving surfaces that are being grinded. Partial flexibility of the working area is achieved by inserting flexible backings between the sander's pressure plate and the abrasive paper. Using the so-called band sanders for sanding of concave and convex surfaces is almost impossible due to the construction of its fixed pressure plate. For optimising of the sander size applies the rule, that the larger the radius, the larger the working area, and vice-versa.

When manual sanding planes are used, flexible tools that are at least partly able to follow the curving radius of the surface being grinded are often used. However, the disadvantages mentioned above still remain.

THE PRINCIPLE OF THE INVENTION

The above-mentioned shortcomings are overcome by a sander designed for sanding of flat, concave and convex surfaces according to this technical solution of the invention, the principle of which consists of the sanding tool (paper, fabric or other carrier with sanding abrasive layer) being pressed onto the grinded surface with the use of a flexible pressure plate able to trace concave as well as convex surfaces with the possibility to set the precise radius of this curve.

The principle of the technical solution of the invention of the flexible pressure plate rests in the fact, that the pressure applied during the work onto the body, the handle or handles of a sander with mechanical drive, is transmitted onto the pressure plate simultaneously at least at two points or through minimally one balance beam. The pressure is advantageously distributed via a bracket to at least two and more points of the pressure plate. The number of pressure points of the pressure plate is given by the number of the balance beams and brackets, through which this pressure is transmitted through the flexible pressure plate with abrasion layer onto the grinded surface. The brackets are firmly fixed to the pressure plate and are connected movably with the balance beams with the use of pins, and in this way, at least one bracket of the pressure plate is able to shift against the balance beam. The balance beam is provided with an opening at one end, and it is statically fixed to the bracket by a pin. At its other end, the balance beam is provided with a notch, in which the pin with bracket can shift, which allows maintaining the flexibility of the pressure plate for shaping of the pressure plate as required by curving of the grinded surface. When two or more balance beams are used, these third and each following balance beam are bridged over by other balance beams, while the bottom balance beams serve simultaneously as brackets. The number of balance beams is not limited. It depends directly on the length of the pressure plate and on the size of the grinded surface. The function of the third and each following balance beam in a pyramid arrangement and the technical design of fixing with the use of pins are similar. The highest placed balance beams are attached in the same way to the body of the sander or, in the case of manual sanding planes, directly onto the handle of such a plane. With the use of the outlined technical solution of the invention, the pressure plate thus pushes the sanding tool onto the grinded surface applying approximately constant pressure along the entire length of the area of the sanding tool, which is then distributed to the whole part of the line of the sanding surface. The solution allows using of sanders with long working surfaces, when the pressure force applied onto this tool is evenly distributed along the whole length of the grinded surface and at the same time, it facilitates optimally accurate shaping of the curvature of the pressure plate according to the required curving of the grinded surface. The required curvature of the pressure plate can be fixed with the use of pull-bars. These pull-bars run from the pins of the pressure plate brackets or from the pins of balance beams to the body or the handle of the sander, which is for this purpose fitted with pivot pins with lateral openings, through which the pull-bars pass freely. This pivot pin is in its axis provided with a lock screw for possible fixing of the position of the pull-bar relatively to this pivot pin. In the case of any bending of the pressure plate, a change in the distance takes place between the axis of the bracket pins or the balance beams against the axis of the pivot pins located on the body or the handle of the sander. If the pull-bar is not fixed against the pivot pin, the flexibility of the pressure plate is not limited in any way. If the pull-bar is fixed against the pivot pin, the flexibility of the pressure plate is eliminated and the plate stays permanently set for the required curvature. The required curvature can be set up, for example, by using a contact template. This technical solution allows sanding of the precisely set radiuses of surface curvatures.

It is possible to cover completely the actual mechanism of the flexible pressure plate with a flexible bellows, inserted between the hard cover and the pressure plate. This bellows is fixed permanently to the hard cover and it is pushed against the pressure plate by flat, shaped springs. This technical solution of the invention does not limit the flexibility of the pressure plate in any way. The cover protects the mechanism against mechanical damage and in addition to that, the hard cover may be used for attaching of a container for extraction of abrasion dust. In that case, the pressure plate and the sanding material are provided with extraction openings.

The flexible pressure plate can be used both for manual sanding planes and for mechanically driven sanders of the linear or band-type.

The principle of the invention of using a flexible pressure plate for linear sanders with mechanical drive consists in the fact, that the bottom surface of the pressure plate is fitted with a minimum of one movable flexible plate, which is mechanically driven and moves linearly between the pressure plate and the surface being grinded. The movable flexible plate is fitted on its bottom side either with any known system for fixing of the sanding tool, for instance sand paper or linen or directly with abrasive material. It is possible to use advantageously a system of two movable flexible plates moving in the same axis of one flexible pressure plate but always in mutually opposite direction.

This technical solution of the invention allows designing a sander with extremely large working surface, whereby two flexible plates with abrasive material, moving against each other, mutually eliminate vibrations and undesirable kinetic forces generated by the sander's drive, which develop due resistance of the grinded surface and the sanding tool. At the same time, it reduces the influence of inertial force of the sanding tool and the reaction to resistance of the working surface in the process of sanding. The flexible movable plate is designed in a way that allows it to move only along the longitudinal axis of the flexible pressure plate, to always implicitly and accurately copy this pressure plate and, at the same time, to have as little as possible effect on the flexibility of the pressure plate. The flexible movable plate is in cross-section made of the C-shaped profile, which partly embraces the pressure plate. At the point where the profile of the plate passes from the side to the top surface of the pressure plate, the entirety of the profile is cut at regular intervals by notches. These notches remove longitudinal rigidity of the profile, allow maintaining of the maximal flexibility of this movable plate, and eliminate its influence on the properties and flexibility of the pressure plate. In addition to that, the embrace ensures that in case of any deflection of the pressure plate the movable plate copies this deflection precisely. Plastic material with the best possible sliding properties was selected as the construction material for the movable plate.

The profile designed in this way can be used for the linear sander, when the plate is fitted with a minimum of one nib used for connecting of linear drive and moves linearly in two directions along the longitudinal axis of the pressure plate, or in the form of an endless band when it moves in one direction as in the known principle of a band-type sander. The function of the C-profile and usage of the flexible pressure plate is the same as for a linear sander.

The technical solution is utilised advantageously for the system using at least two and more, mutually connected, pressure plates and at least two and more sanding belts, where these belts move in opposite directions. This eliminates mutual resistances, kinetic pressures and tensile forces of the tool, and the momentum forces developed during the sanding process. It is possible to adjust advantageously the speed of individual abrasive bands and thus aid the sander in its movement along the grinded plate.

SUMMARY OF ILLUSTRATIONS IN DRAWINGS

The technical solution of the invention will be explained in more detail with the use of drawings, which illustrate the following:

FIG. 1 shows the manual sanding board according to the technical solution of the invention with the flexible pressure plate, where the pressure is applied from the handle of the plane through two balance beams. In this case, the handle also serves as an independent third balance beam.

FIG. 2 shows a similar construction of the manual sanding plane fitted with a cover, fixing pull-bars and dust extraction.

FIG. 3 shows Section AA through the detailed construction design of the fixing pull-bars for fixing of the set radius for the curvature of the flexible pressure plate.

FIG. 4 shows the cross-section with the detail of fixing the flexible bellows

FIG. 5 shows the principle of the linear machine sander with the pressure plate and one movable flexible plate, and the use of this sander for sanding of a flat surface.

FIGS. 6 and 7 show the usage of the same sander for sanding of convex or concave surfaces.

FIG. 8 shows the principle of the large-area linear machine sander with flexible pressure plate and two, counter-running movable flexible plates.

FIG. 9 shows the section through the flexible pressure plate with movable C-profile-shape plate and its partial embracing of the flexible pressure plate and the nib (carrier) for connecting of the linear drive.

In FIG. 10 is the view of the flexible pressure plate with flexible movable plate with lateral notches. The plate is provided with one nib (carrier) for connecting of linear drive.

In FIG. 11 is illustrated the detail section at lateral notches of the C-profile, which eliminate longitudinal rigidity of the profile.

In FIG. 12 is illustrated the principle of bending of the pressure plate and of the movable sanding plate.

In FIG. 13 is illustrated the use of the C-profile in the form of an endless band of the band-type sander with two guiding pulleys.

In FIG. 14 is the section through the guiding pulley.

FIG. 15 shows the use of the flexible pressure plate on the band-type sander for sanding of a flat surface.

FIGS. 16 and 17 show utilisation of the same sander for sanding of convex and concave surface.

FIG. 18 shows the principle of large-area band-type sander with two flexible pressure plates and with two opposite-running bands.

In FIGS. 19 and 20 is illustrated the usage of identical sander for sanding of convex or concave surface.

INDEX LIST

-   1—Basic flexible pressure plate, -   2—Sponge rubber, -   3—Dry zip, -   4—Bracket, -   5—Pin, -   6—Pin, -   7—Notch, -   8—Balance bar, -   9—Pin, -   10—Pin, -   11—Notch, -   12—Balance bar, -   13—Handle, -   14—Sanded surface, -   15—Cover, -   16—Flexible collar, -   17—Coupling, -   18—Through-hole, -   19—Pull-bar, -   20—Tube, -   21—Pin, -   22—Locking screw, -   23—Flat spring, -   24—Rivet, -   25—Rectangular profile, -   26—Opening, -   27—Movable profiled plate, -   28—Abrasive material, -   29—Flexible pressure plate, -   31—Lateral notch, -   32—Carrier, -   33—Notch, -   34—Flexible pressure plate, -   35—Movable sanding plate, -   36—Movable sanding plate, -   37—Endless profiled sanding band, -   38—Abrasive material, -   39—Flexible pressure plate, -   40—Toothing, -   41—Notch, -   42—Pulley, -   43—Stirrup

INVENTION EXECUTION—EXAMPLES Example 1

The sander or, more precisely, manual sanding plane (see FIG. 1) comprises of the basic flexible pressure plate 1, which is fitted on its bottom with sponge rubber 2 and a dry zip 3 for attaching of the sand paper. On the pressure plate are located the brackets 4 with pins 5 and 6. The brackets are connected in pairs by balance bars 8, which are provided at one end with an opening for pins 5 and on the other end with a notch 7 in which moves the pin 6. The movement is initiated by any deflection of the pressure plate 1 resulting in a change of the distance between pins 5 and 6. The balance bars 8 include pins 9 and 10. The balance bars 8 are mutually bridged over by balance bar 12 which is provided at one end with an opening for pin 9 and on the other end with a notch 11, in which moves pin 10 passing through the hole in the balance bar 8. The function of balance bars 8 and 12 is to distribute evenly the pressure applied onto the handle of the sanding plane along the entire length of the pressure plate 1, which presses the abrasive material evenly onto the surface being grinded 14 and this applies also to sanding of the concave or convex surfaces. To the highest-placed balance bar 12 are fixed the ergonomically shaped handles 13.

Example 2

The manual sanding plane (see FIG. 2) is of a similar construction to that of the above plane (see FIG. 1). It is supplemented by a firm plastic cover 15 with a flexible collar 16 and coupling 17 for connection of the hosepipe for extraction of abrasion dust. For this reason, there are through-holes 18 for extraction of the abrasion dust in the pressure plate. The pressure plate is also provided with pull-bars 19 that are fixed against the upper balance bar, and thus the fixing of the curvature of this pressure plate is allowed.

The detail of the functioning and of the construction of the balance bar 19 is apparent from Section AA in FIG. 3. The balance bar 19 is firmly connected with the tube 20, which is pulled over pivotally on pin 5. At the same time, the balance bar 19 passes freely through the lateral opening in pin 21, placed pivotally across the upper balance bar or, more precisely, the handle of the sander 12. In the longitudinal axis of this pin 21 is a threaded opening for the locking screw 22. If the locking screw 22 is loose, the balance bar 19 can move freely through the lateral opening in pin 21 and it does not limit in any way the flexibility of the pressure plate 1. Once the locking screw 22 is tightened up, it pushes the pull-bar 19 and fixes against the pin 21 and therefore against the sander handle 12 and at the same time, it fixes the point that crosses the longitudinal axis of the pull-bar 19 with pressure plate 1. In order to achieve the most accurate setting and the firmest fixing of the pressure plate to the required radius of the curved or flat surface, it is advantageous to fix as many as possible points, i.e., to use as many as possible pull-bars.

The detail of the fixing of the flexible collar 16 is illustrated in the section in FIG. 4, where the flexible collar 16 is firmly attached to the hard cover 15. The flexible collar 16 is pressed against the flexible pressure plate 1 only with the use of the shaped flat spring 23 connected permanently to the flexible pressure plate 1 by rivets 24. In addition, the collar is provided in its bottom section with a reinforcing rectangular profile 25, through which springs 23 press evenly the bottom section of the collar 16 to the upper surface of the pressure plate 1. The reinforcing profile is provided with openings 26 into which the ends of the shaped springs 23 jump. Since the flexible collar is not firmly connected to the pressure plate, any deflection of the pressure plate results in the bottom surface of the collar moving independently to the upper surface of the pressure plate, while not limiting in any way the flexibility and properties of the pressure plate 1.

Example 3

The linear machine sander with flexible pressure plate (see FIG. 3) is based on a similar construction and principles as the manual sanding plane (see FIGS. 1 and 2). In addition, the flexible pressure plate 29 is fitted with mechanically driven movable profiled plate 27 fitted on its bottom with abrasive material 28. The plate is designed as the C-profile that partly embraces the flexible pressure plate 29. The view and the section of thus profiled movable sanding plate embracing the flexible pressure plate are shown in FIGS. 9 and 10. The profile of the movable sanding plate 27 is on its top side lightened by lateral notches 31 made at regular intervals, which removes longitudinal rigidity of the profile. The detail of the lightening is illustrated in FIG. 11. The principle and behaviour of the lightened profile 27 towards the pressure plate 29 during concave or convex deflection of this plate is illustrated in FIG. 12. This construction of the movable sanding plate 27 enables the movable sanding plate 27 to copy continually the pressure plate 29 at any deflection of the pressure plate 29 in particular during sanding of concave and convex surfaces.

In addition, the profiled plate 27 is fitted with a nib (carrier) 32 designed for connection of the linear drive. For this reason, the flexible pressure plate 29 is fitted with a notch 33 in which this nib (carrier) 32 moves linearly. As the material for construction of this movable sanding plate was selected the plastic with very good sliding properties (Teflon or similar).

Once the flexible pressure plate 29 and movable plate 27 are provided with extraction openings (similar to the openings 18 in FIG. 2), this construction allows the covering of the whole mechanism in a way that is similar to the covering of the sanding plane (see FIG. 2) and connecting the sander to the extraction of abrasive dust.

Example 4

The large-area linear machine sander with flexible pressure plate 34 (see FIG. 8) is based on the principle similar to the one used for the above-mentioned sander (see FIGS. 5, 6, and 7). The main difference from the above-mentioned sander is the fact, that the flexible pressure plate 34 is not fitted with one but with two movable sanding plates 35 and 36. These plates move linearly along the axis of the pressure plate 34 always in opposite directions against each other. This solution allows substantial elimination of any resistances from the sanding tool, as the forces, applied on both the plates with abrasive material are applied in opposite directions and therefore cancel each other. Another advantage of this design is the substantial increase of the size of the sanding surface. The functioning and the principle of the flexible pressure plate 34 and the ability to shape this plate according to the concave or convex surface is maintained.

Example 5

It is possible to use advantageously the principle of the flexible pressure plate also for the band-type sander with endless abrasive band (see FIG. 15). The movable sanding plate or, more precisely, the C-profiled movable sanding plate is in this case made as the endless profiled sanding band 37 fitted with abrasive material 38, which runs in one direction over the minimum of two pulleys, with at least one of these being the driving pulley. Again, the band is pressed onto the grinded surface with the use of the flexible pressure plate 39 allowing the sanding of concave or convex surfaces. The principle of embracing the pressure plate 39 with the profiled sanding band 37 is similar to the one used for the linear sander with profiled sanding plate (see FIG. 10). The profiled band has no nibs or carriers. The band is put into motion only by the adhesion between the band and the driving pulley or the toothing 40 of the pulley 42, which fits into the notches 41 of the sanding belt 37. FIG. 14 shows Section CC through the guiding or the driving pulley 42 with the principle of guiding the sanding profiled band 37.

In FIGS. 15, 16, and 17, in Section DD, is illustrated the principle of usage of the flexible pressure plate for sanding of flat, convex, and concave surfaces.

Example 6

The large-area, band-type machine sander (see FIG. 18) is based on the principle similar to the one used for the sander illustrated in FIGS. 15, 16, and 17. In this case, two flexible pressure plates 39 are used, connected together with a 43 stirrup and provided with two endless sanding bands 37, which move in opposite directions against each other. The speed of these sanding bands is electronically regulated, so that the speeding-up or slowing-down of one of the bands against the other one makes the whole sander to move along the grinded surface and to eliminate partly the physical exertion required during the work with this sander. In the other aspects, this technical solution of the invention offers the same advantages as the similar movement of the plates moving in opposite direction of the sander illustrated in FIG. 6. FIGS. 19 and 20 illustrate the deflection of the pressure plates 39 during sanding of convex and concave surfaces.

INDUSTRIAL UTILITY

The technical solution of this invention is utilizable in particular for design of new manual sanders or for the sanders with mechanical drive used for sanding of large flat, concave, convex surfaces, and it describes various advantageous methods of improving the sanding operations with the use of the above-mentioned tool.

ANNOTATION

The sander for sanding particularly of the flat, concave and convex surfaces and the method of its usage is based on the fact, that the sanding tool (paper, linen or other carrier with sanding abrasive layer) is pressed onto the grinded surface by means of a flexible pressure plate able to copy the concave and convex surfaces with the possibility to set accurately the radius of this curve. The principle of the technical solution of the invention of the flexible pressure plate consists in the fact, that the pressure generated during the work onto the body, handle, or handles of the sander with mechanical drive is transferred onto this pressure plate at least at two points simultaneously or over at least one balance beam. 

1. A sander used in particular for sanding of flat, concave, and convex surfaces characterized by that it comprises of at least one flexible pressure plat, at least one Balance bar, at least one bracket, at least one pin, at least one Pull-bar, and sanding tools.
 2. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that, the bracket is tightly connected to a pressure plate and movably connected to pull-bar using pins, so as to allow drift of at least one bracket of the pressure plate with respect to a balance bar, where the balance bar is at its end fitted with an opening (26) and mounted statically to a bracket using a pin.
 3. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that, the balance bar is at its end fitted with a notch, into which the pin and bracket are mounted in a movable way.
 4. A sander used in particular for sanding of flat, concave, and convex surfaces according to any convex surfaces according to claim 1 characterized by that, in case of two or more balance bars the third and any addition balance bars are fitted with bridging via other balance bars, where the bottom balance bars are also used as brackets.
 5. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that the pull-bars lead into pins of pressure plate or even pins of balance bars of the body or to a holder of a sander fitted with revolving pins with lateral opening allowing free passage of the pull bar.
 6. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that the pin is in its axis fitted with a locking screw to affix the position of the pull-bar to this pin.
 7. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that it is completely covered by a stationary cover preferably a flexible bellows, that is pressed down using flat shaped springs, where the cover is fitted with openings for abrasion dust suction in case the pressure plate and the sander material are fitted with suction openings.
 8. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that the flexible pressure plate of the sander is fitted with mechanical drive actuator embodying a bottom surface of the pressure plate fitted with at least one movable profiled plate with mechanical drive moving linearly between the pressure plate and the sanded surface, where the bottom surface of the movable profiled plate is fitted with a known system for affixing the sanding tool, mainly sanding paper or cloth or even abrasive material.
 9. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that it comprises at least two or more flexible pressure plates moving in the same axis of a single flexible pressure plate, but always in reciprocally opposite direction.
 10. A sander used in particular for sanding of flat, concave and convex surfaces according to any of the claim 1 characterized by that in the area where the pressure plate profile verges from side surfaces to top surface of the pressure plate, the pressure plate profile is evenly fitted with lateral notches.
 11. A sander used in particular for sanding of flat, concave, and convex surfaces according to claim 1 characterized by that it comprises at least two or more interconnected pressure plates and at least two or more sanding belts with adjustable speed, where these belts move in reciprocally opposite direction.
 12. A sander used in particular for sanding of flat, concave, and convex surfaces characterized by that the sanding tool is pressed to the sanded surface by a flexible pressure plate which is able to follow concave and convex surface with an option of accurate setting the radius of such a curve.
 13. A method of sanding flat, concave and convex surfaces with a sander according to claim 12 characterized by that the generated pressure on the body, holder, or sander holder with mechanical drive is transmitted simultaneously to a pressure plate in at least two or more areas and/or over at least one or more balance bars.
 14. A method of sanding flat, concave and convex surfaces according to claim 12 characterized by that an identical pressure is applied to at least two or more places of the pressure plate using preferably a bracket.
 15. A method of sanding flat, concave and convex surfaces according to claim 12 characterized by that the pressure plate presses the sanding tool (paper, cloth or other carrier of abrasive layer) to a sanded surface in all the length of the sanding tool applying approximately constant pressure, which is evenly applied on the entire line of the sanding surface.
 16. A method of sanding flat, concave and convex surfaces by a sander according to claim 1 characterized by that the curvature of the pressure plate can be affixed using pull-bars.
 17. A method of sanding flat, concave and convex surfaces by a sander according to claim 12 characterized by that the curvature is set using a stoking template.
 18. A method of sanding flat, concave and convex surfaces by a sander according to claim 12 characterized by that abrasion dust suction is also ensured by that a flexible cover plate is pressed through a sealing rubber to a top part of another flexible pressure plate where between these two plates there exists an enclosure where the cover plate is not connected to the pressure plate in any solid way thus having on vital effect on the flexibility of the pressure plate.
 19. Utilization of the sander and method of sanding flat, concave and convex surfaces with manual abrasive planes, as well as machine driven sanders either linear or band-type according to claim
 1. 